ECU wanted for 1991 TZI

[TZI]

Just heard back from the ECU repairers - no fault found! (http://ecutechnologies.co.uk, £54 inc VAT & carriage).
Not sure whether that is good news or bad news?
What it does mean is that it is back to the drawing board!
Away from home at the moment but hopefully will have some lighter evenings next week to look again.
First need to find out why now zero volts at the injectors, get 5 volts back and take it from there.

[rutter123]

It may be worth checking the wiring loom for the injectors, i had similar probs with my gti due to dry joints on the injectors as they are only crimped together and not done particularly well, my gti suffered endless running probs, last resort was to completely remove the entire loom strip it all down unwrap it and solder all the crimped joints and clean up and fit new terminals on all ground connectors to the inner wing, i also re- located the coil whether this had any bearing on issues im not sure but the probs now seem to be cured and the car is certainly running a lot better, without a plug in diagnosis its just a process of elimination very slow and long winded. As a last resort i completely stripped every component off down to the bare engine, re-fitted checked, double checked, triple checked each component also found a few broken wires (due to age mostly) on the coil plug and the temp sensor and throttle position switch hence these plugs have been cut off and replaced with 4mm insulated terminals.
Best of luck.

[Kaapelimies]

I'm not sure if it's a global thing in BX TZI's, but in finnish climate they tend to oxidize the wiring connections over the right (drivers in your case) side inner wing. We find here thet there's only white powder where the copper wire was once. Symptoms are not lighting the K-light (no power to ECU), no power to fuel pump or no power to injectors. All problems can be measured from the ECU connector and traced back using the schematic diagram (where the connections are not shown!).

Bought 2 TZI's with this problem, another one is still not drivable because it needs new fuel lines and possibly fuel pressure regulator, these tend to be very cheap as not even many garages manage to fix these .

[Way2go]

Just heard back from the ECU repairers - no fault found!

I did think that would be the case but I understand why you thought it as I was leaning that way on mine until I discovered gummed up injectors.[/quote]

First need to find out why now zero volts at the injectors, get 5 volts back and take it from there.

Why 5volts?

They do not have a measurable voltage as they are given a pulsed waveform when the engine is running. If you wanted to see electrical activity here, you would have to use an oscilloscope not a voltmeter. A single short pulse or 2 before starting is likely all the engine needs to get going if all else is good with the engine.

PS: Beware, because the injectors are designed for pulse and mark/space operation, you are likely to burn out their coils if you apply any permanent voltage to them (& also damage the ecu if that was still in circuit).

[citronut]

as i suggested earlier the OP requires to test for injector pulse

http://www.ebay.co.uk/itm/SALE-NOID-LIG ... 4897.l4275

regards malcolm

[TZI]

I appreciate that is there is pulse to the injectors when the car is running but the check I was doing was with the engine not running but the ignition on. According to what I have read (see the link earlier in this thread) in this state there should be a static voltage to the injector. According to this article:
http://citroen.tramontana.co.hu/fuel-ex ... components
the Motronic 1.3 system puts out 5 volts and this was what I initially measured. This was just to check whether the ECU was putting out power. I won't worry about fuel delivery until car is sparking consistently and the car is still not running.

[TZI]

I will check the wiring again and a bit more thoroughly and perhaps do some impedance checks with the ECU disconnected.
Kaapelimies - you say over the right inner wing (looking from the drivers seat of a RHD car). On mine this where the fuel pump and ignition relays sit. Apart from that there are just some wires that disappear into the wheel arch area. Are you just talking about the wires to the relays?
On the opposite side underneath the battery tray are a gaggle of block connectors and wires that go through the bulkhead to where the fuse and relay box sits (above the passengers feet). I have checked these as best I can and all seem intact. In your experience do these also cause trouble?

[Kaapelimies]

Apart from that there are just some wires that disappear into the wheel arch area.

Exactly these wires. You'll have to remove the wing to get access to the connections. You may see them underneath by removing the plastic inner arch, but there's a lot of tape over the wires that has to be removed. I'm trying to find some pictures but I'm not sure if I have taken any..

Edit found some but they are inside the wing (click to open album):

[TZI]

That's a great help - next week I will get under the inner wing and see what I find. I think the charcoal canister is under there too?

[Kaapelimies]

I think the charcoal canister is under there too?

Yes.

[Tim Leech]

It is on mine.

[TZI]

I had a look under the wing and at first sight the wiring looked sound.
Noticed that the 'K' light on the dash was not coming on with the other red ignition lights (this was after noting no voltage at the injectors or at the crank sensor).
Decided that there must be no power to the ECU so set out to track back from there.
Then I checked the wires to the ignition relay (ignition on) and those were now all dead. It seems that the ignition lights (red ones) all come on even if the 'ignition relay' is dead.
The larger yellow wires from the relay went under the wing into the area in which Kaapelimies photos were taken. I gave a tug near a taped joint and the wire 'came away in my hand guv'.
Stripped the wires (4) and made a temporary repair with a block connector (3 into 1).
Ignition on, 'k' light on and the car fired up sweet as you like.
Many thanks to everyone for the advice and support. Special thanks to rutter123 for wiring corrosion warnings and extra special thanks to Kaapelimies for getting me to take the wing off. I would never have bothered doing that. I got lucky in that the intermittent issue became a permanent one but without your help another BX would be scrap.
Kaapelimies, if you ever come to Bristol I would like to buy you a warm beer!

[Tim Leech]

Awesome!

Glad it's all done!

[Kaapelimies]

Watch out what you promise, if somewhere's free beer available, in no time there are the finns
Glad I could help.